Rotary relay and contacts therefor



June 24, 1947. c, p, MQLYNEUX r A 2,422,842

ROTARY RELAY AND CONTACTS THEREFOR Filed Sept. 29, 1943 2 Sheets-Sheet 1 l Hill z nnm MMfiMMWMM mail J1me 1947- c. P. MOLYNEUX ET AL 2,422,342

ROTARY RELAY AND CONTACTS THEREFOR Filed Sept. 29, 1943 2 Sheets-Sheet 2 Patented June 24, 1947 UNITED STATES PATENT'OFFICE ROTARY RELAY AND CONTACTS THEREFOR Cecil Patrick Molyneux, Great Neck Estates, and Vernon D. Roosa, Ardsley, N. Y., assignors to Queensboro Manufacturing Company, Long Island City, N. Y., a partnership Application September 29, 1943, Serial No. 504,224

28 Claims. 1

The present invention relates to a rotary relay and contacts thereof and, more particularly, to such a relay employable in the regulation of generator voltages.

A general object of the present invention is the provision of a rotary relay which is of simple and sturdy construction, can be readily and economically manufactured, and which will efiiciently control external circuits with a high degree of accuracy without undue hunting and overthrow while effectively minimizing contact sparking and arcing; and novel contacts thereof which in operation of the rotary relay are effectively selfcleaning to eliminate resisting oxides, mechanically self-aligning while providing for automatic removal of pits and transferred contact material and which provide for rapid and effective quenching of sparks.

A more specific object of the invention is the provision of such a. rotary relay in which the movable contact ls effectively operated by a rotating plunger which in its rotation inherently develops a damping effect without necessitating employment of mechanical damping means.

Another object of the invention is the provision of such a. rotary relay which by variations in the excitation of a field winding thereof corresponding variations in contact pressure, and consequently in contact resistance, are produced in accurate accord with the variations in the field excitation without necessitating complete breaking and making of contact, except under extreme conditions, thereby assuring a highly delicate responsive action.

A further object of the invention is the provision of a rotary relay which is characterized by a floatably mounted rotor biased to a. displaced position with respect to the stator whereby variations in the excitation of the field winding on the stator or rotor gives small variations in axial movement of the rotor accurately to control circuit contacts.

Still another object of the invention is the provision of such a rotary relay which may be eificiently employed as a voltage regulator for electrical generators to regulate the output voltage thereof with high accuracy and which will also efficiently operate as a frequency or speed regulator.

A still further object of the invention is to provide such a rotary relay as a voltage regulator by providing for connection of the field winding thereof to the output circuit of a, generator and shunting of the contacts (controlled by axial movement of the rotor) across a resistance in 1 2 the field circuit of the generator to effect accurate regulation of the voltage 01 the Output circuit of the latter, or which may be employed in the emcient control of other electrical devices.

An additional object of the invention is the provision in such a rotary relay of a relatively fixed contact and a cooperating rotary contact with one thereof provided with cutting edges to keep the contact face of the other during contact rotation efliciently clean and relatively free from resisting oxides, pits and transferred contact material.

Another additional object of the invention is to provide such a pair of contacts wherein a transvers groove in one contact face provides cutting edges to give a milling effect for keeping a cooperating contact face relatively clean and smooth and accurately aligned with the grooved contact face, which groove may be provided on the rotary contact to create air turbulence and a fan effect for eflicient spark quenching.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is an elevational view with parts in section and broken away, of one embodiment of the rotary relay oi the present invention, showing one axial position of the rotor thereof;

Fig. 2 is a view similar to Fig. 1 showing another axial position of the rotor thereof;

Fig. 3 is a detailed view, with parts in section and broken away. of a modified form of the contact structure shown in Figs. 1 and 2;

Figs. 4 and 5 are enlarged perspective views of the contacts shown in Fig. 3;

Fig. 6 is a diagrammatic view of a. regulator system for electrical generators, employing an embodiment of the rotary relay of the present invention;

Fig. 7 is a reproduction of portions of an Esterline-Angus curve showing frequencies plotted against time and indicating typical operation of the system 01' Fig. 6: with such time interval portions of the curve as were merely substantially repetitive and in hich only slight variations appeared being omitted in the dotted portions thereof;

Fig. 8 is a showing similar to Fig. 7 with voltage plotted against time; and

Fig. 9 is a detailed fragmentary view similar to Fig. 3 showing a modified form of support for the relatively fixed contact.

The present invention comprises a rotary relay for controlling electrical circuits which as indicated above may be the output circuit of electrical generators with the rotary relay acting as a regulator. The rotary relay includes an electric motor having a rotor and a stator with one of those elements including a field winding adapted to be supplied with control current. It will be understood that a variety of types of electric motors may be employed for this purpose since, as will appear hereinafter, the speed of operation of the motor is relatively immaterial to the functioning of the device. Thus the motor may be of the induction type with the rotating magnetic flux due to current taken from the supply line being carried by coils or field windings which may be on either the rotor or the stator. The rotor is floatingly mounted by suitable bearing structure and is normally biased to an axially displaced position with respect to the stator. This biasing may be accomplished by means of resilient structure, such as a spring, or by the force of gravity, or by both acting in conjunction with each other, or by any other suitable means such as by magnetic biasing. The rotary relay includes a pair of cooperating contacts which are adapted to be connected in circuit with an electrical device for controlling flow of current therethrough. One of these contacts is mounted in a relatively fixed manner, and the other is movably supported by structure mechanicall connecting it to the rotor so that the latter in its axial movement will cause movement of the movable contact toward and away from the relatively fixed contact, either to vary contact pressure or to make and break the circuit.

In a particular embodiment of the invention the movable contact is carried as a rotary element by the shaft of the rotor, although it will be understood that the movable contact might, if desired, be supported upon non-rotating structure such as an arm .to be moved toward and away from the relatively fixed contact by axial movement of the rotor shaft. Further such contacts may be so constructed as to provide for effective self-cleaning and mechanical self-alignment, such as by the provision of cutting edges on the contact face of one for milling of a relatively smooth contact face on the other. For this purpose the cutting edges may be provided either on the relatively fixed contact or on the rotary contact, so that the work rotates relatige to the tool or the tool rotates relative to the work. Preferably the cutting edges are provided on the rotary contact; so that in their formation, such as by a transversely extending groove or grooves, the side walls of the groove or grooves may provide fan action for efflcient spark quenching. Preferably one of the contacts is provided with a plurality of medially intersecting grooves and the.

other contact is medially provided with a recess so that as the cutting edges mill of! the surface of the latter in a circular path the action will not result in the gradual formation of a central projection which might tend to give excessive contact arcing.

For a more complete understanding of the invention reference may be had to the accompanying drawings in which like numerals refer to like parts throughout. In Figs. 1 and 2, a particular embodiment is shown which may comprise a base plate l0 suitably supporting a casin ll of an electric motor which, as indicated, may be of the squirrel cage type having a, rotor I! fixed upon a shaft l3 rotatably supported by bearings H and IS. Th stator l6 comprises a field winding adapted by means of suitable terminals i not shown) to be connected to a supply circuit for fiow of control current therethrough.

A indicated the bearing 14 permits both rotary and axial movement of the shaft l3 and the other bearing element 15 may comprise a cup of electrically conductin material having a disc I! or carbon therein against which the lower end of shaft l3 rotatably seats. Shaft I3 is made of any suitable electrically conducting material and may, if desired, be fitted at its lower end with a copper facing for rotation against the carbon disc II to provide an efficient current transfer device. The cup member I5 is provided with a plunger I8 reciprocatively fitted into a fixed sleeve is which may be formed of any suitable electrically conducting material such as brass. The outer end of the bore through the sleeve I9 is preferably internally threaded to receive an axially adjustable abutment screw 20 between the inner end of which and the plunger It a biasing helical spring 2| is located. The screw 20 is suitably fitted with a control knob 22 and a terminal connection 23 may be provided on the sleeve l9 as shown.

Rods 24, 24 mounted upon the motor casing II may support mounting means for a relatively fixed contact. This means may comprise a crossmember 25, preferably of insulating material, having a hole therein through which a threaded shank 26 of a headed relatively fixed contact member 21 extends for engagement by a mounting nut 28. A conductor strap 29 may be clamped beneath the nut 28 electrically to connect the contact 21 to a circuit terminal 30.

The electrically conducting shaft I3 preferably carries at its upper end a rotary contact 31 biased to face-to-face engagement with the relatively fixed contact 21 by means of the biasing spring 2 I,

It will be seen from an inspection of Fig. 1 that normally the biasing spring 2| hold the rotor l2 upwardly slightly out of alignment with the stator IS in bringing about a circuit closing condition at the contacts 21 and 3| and when control current is supplied to the field winding, such as the stator IS, the rotor l2 rotates at a relatively high speed with those contacts in face-to-face engagement and with the rotor slightly out of alignment with the stator. Increase in excitation of the field winding will increase the magnetic force of the stator to cause it to-tehd to pull the armature l2.down into alignment-such the stator IS in opposition to the biasing force of the spring 2| The force of the magnetic field may eventually become great enough to overcome the biasing force of the spring 2|- resulting in the armature I2 being pulled down into alignment with the stator I with an attendant separation of the rotary contact II from the relatively fixed contact 21, which extreme condition is indicated in Fig. 2.

This rotary relay, however, does not depend for functioning upon complete make and break of a circuit at the contact since it has been found that the device will effectively operate to vary the contact pressure with an attendant variation in the resistance. This is distinctly different from the operation of an ordinary plunger solenoid as has been found by tests. Plunger solenoids are known to produce hunting and overthrow where operation is dependent upon vibratory operation of contacts accompanied by complete make and break. For certain services it is thus found to be necessary to use some type of mechanical damping means which in turn reduces sensitivity of the apparatus. The rotary relay of the present invention inherently operates with an automatic damping effect which may be due to the rotating mass or rotor having gyroscopic action tending to resist mechanical axial movement and may be due in part to some sort of air dashpot effect. In any event, the rotor acting as a plunger has an unusually high freedom of action and operates with extreme sensitivity. This was observed by stroboscopic inspection of the contacts during variations in flow of current through a circuit including the contacts which was accomplished by small variations in excitation of the field winding. It was found that with an ohmmeter connected across the contacts showing variations there was no visual evidence of contact separation, except under extreme conditions, which indicated that the rotary relay operated with a varying contact pressure characteristic, thereby avoiding excessive arcing and sparking which are troublesome features of other types of relays. This rotary relay has been found accurately and quickly to respond to small changes in the electromotive force in the field winding thereof, and there is a minimization of loss effect.

As shown in Fig. 3 an embodiment of the rotary relay of the present invention may be equipped to advantage with special types of contacts. The relatively fixed contact I21, as is more clearly indicated in Fig. 4, may be provided with a rela tively smoothtransversely extending contact face 32 having a centrally located recess 33 formed therein for a purpose to be indicated hereinafter. The rotary contact I3l may have a threaded shank I26 and a transversely extending contact face 34 provided with a plurality of cutting edges 3535 formed preferably by intersecting transversely extending grooves 36, 36. Preferably the contact I2! is made of material softer than that from which the contact l3l is formed. For example, the head of contact I21 may be formed of silver and that of contact l3i of tungsten so that in the rotary movement of the latter the cutting edges 35-35 will effectively mill the contact face 32. As a result the contact face 32 is kept free of resisting oxides and pits and is kept in accurate alignment with the contact face 34 of the rotary contact I3i. This milling of the contact face 32 would eventually result in the formation of a central projection on the face of contact I21 due to the lack of cutting edges in the medial portion of the rotary contact II". To prevent this occurring the contact I2! is provided with a central recess 33.

It will be understood that contacts I21 and I3! may be mounted in reverse order so that contact I2! is made rotary while contact I3! is made relatively fixed so that the work rotates while the tool remains fixed. However the order of mounting, as shown in Fig. 3, is preferable since the side walls of the grooves 36, which are preferably made with substantial dimensions as shown, may operate during the rotation of contact i3| with a fan action to create air turbulence Which has been found to result in very rapid quenching of sparks that do occur when these contacts are infrequently separated during the operation of the rotary relay.

The rotary relay of the present invention may be employed to advantage in the control of electrical circuits of various types of electrical de vices, for example in flashing signs, whereir. the bank of lights could be connected in series with the control contacts 2! and 3| of the rotary relay and with a source of power. The field winding, such as that of the stator l6, could be connected in series with a source of power and a resistance with the latter shunted by a controlling switch to vary the excitation of the field winding. As a result control contacts could be made to govern the power circuit of the bank of lights when the control switch, shunting the resistance in the field winding circuit, was operated. Consequently there would be no complete open circuiting of the field windings thereby avoiding a common-- place problem of frequent repair and maintenance of switch contacts.

The rotary relay of the present invention is particularly adapted to use as a voltage regulator for electrical generators. For this purpose the control contacts of the rotary relay may be connected in shunt to a resistance or rheostat in the field circuit of an electrical generator whether it be of the D. C. or A. C. type. By way of example a voltage regulator circuit is diagrammatically shown in Fig. 6. A three phase A. C. generator is there shown with its armature windings 31 connected to output lines 3838. The generator field winding 33 is connected in series with an exciter 40 in the usual manner and as is common practice a rheostat or variable resistance 4| is connected in series with the field 42 of the exciter 40. For automatic control of the voltage in the generator 31 the rotary relay field windings l8, I are connected by wires 43 and 44 to output lines 38, 38. A conductor 45 connects one side of the field resistance 4| to the terminal 30 which in turn is connected to the relatively fixed contact 21. Another conductor 46 connects the other side of the field resistance 4| to the terminal connector 23 which has electrical connection through the bearing means l5 and rotor shaft l3 with the rotary contact 3 I.

In operation, with the rotary relay of the present invention acting as a regulator for an electrical generator, upon increase in the. voltage in the output circuit of the generator 31 the field force of the stator windings IS, IS also increases. This tends to pull the rotating rotor I2 downwardly into alignment with the field windings l6, IS with such movement being resisted by the biasing force of the spring 2|. As a consequence, the contact pressure at the contacts 21 and 3! is decreased resulting in a higher resistance in the circuit (wire 45, terminal 30, contacts 21 and 3|, shaft l3, current transfer device l5, terminal 23, and wire 46) connected in shunt to the field resistance 4|. Thus there will be more effective resistance in the field circuit of the exciter which results in a lowering of the excitation of the field circuit of the generator with a consequential lowering of the line voltage. When the line voltage of the generator drops due to change in load conditions there is an accompanying weakening of the excitation of the field windings IS, IS of the rotary relay with a consequential increase in contact pressure. This in turn decreases resistance in the shunting circuit which results in a reduction in the effective resistance in the generator field circuit. The attendant increase in excitation of the field winding of the generator causes an increase in the line voltage. The rotary relay oi the present invention will accurately and substantially instantaneously respond to such variations of slight degree giving an unusually accurate control of the output line voltage. It has been found in actual operation that only under extreme conditions where full load on the generator is completely withdrawn substantially instantaneously will the rotary relay completely break contact at the contacts 21 and 3| to make completely efiective the field resistance H which might result in an overthrow, commonly characteristic of all substantial changes of load on generators equipped with well known makes of regulators now commonly used.

The highly sensitive nature and accurate control of generators with the rotary relay of the present invention is graphically shown in Figs. 7 and 8. These two figures represent portions of Esterline-Angus curves which were traced (from right to left) in the test operation of a system such as that diagrammatically shown in Fig. 6 employing the rotary relay of the present invention set to control the line voltage at 250 volts and the frequency at 60 cycles with an accuracy of plus or minus Dotted portions of these two curves represent omitted portions which were merely substantially repetitive and in which only slight variations appeared, thus to permit a clearer showing of the more important portions of the curves in these two figures. Fig. 7 shows the characteristic frequency changes that occurred in progressively changing the load on the system oi. Fig. 6 from no load to a load of 39 amperes, then to full load oi '78 amperes, then back to a load of 39 amperes, and thereafter to no load, and finally from no load to full load. back to no load, and finally again to full load, as a result 01 changes in speed of the prime mover due to widely varying load. The excellent overall voltage regulating ability of the rotary relay of the present invention will be evident by a study of Fig. 8 in comparison with Fig. 7, Fig. 8 indicating the surprising results obtained in the regulation of the voltage of the generator. Fig. 8 shows that despite the characteristic wide variations in frequency the rotary relay operated etfectively as a voltage regulator and, more particularly, that there was no tendency to overswing to any material extent except at the point of load change which produces the worst condition, that is, a change from full load to no load indicated at the point X in the voltage curve. For comparative purposes this same system was operated in a similar manner with the employment of a well known and approved type 01 regulator which is now commonly used and it was found that, for example, in the voltage curve there was an overswing at every load change comparable in amount to that indicated at the point X in Fig. 8. Thus by test the simple rotary relay of the present invention, which can be economically manufactured at a much lower cost than other relays on the market having approved operational characteristics, has proven to give better performance.

Further as contrasted with the operation or vibratory regulators, contact arcing and sparking is minimized. In the present rotary relay in the regulation of line voltages of generators the rotary relay of the present invention operates a major portion of the time without a complete breaking of the circuit shunting the field resistance thereby avoiding tendency to arc or spark at the contacts and only occasionally under extreme conditions where, for example, change from no load to full load is made, are the contacts separated to produce arcing and sparking. The rotational movement of the rotary contact tends rapidly to quench such arcing and when the contact of Fig. 5 is employed which will create a fan effect and air turbulence, there is even greater tendency to rapid arc quenching. The automatic and continual conditioning of the contact surface by the milling effect further reduces tendency to sparking and arcing,

In using the rotary relay of the present invention as a voltage regulator for electrical generators, any tendency to overrun and underrun with the most drastic changes of load conditions can be minimized by employing a ballast tube comprising a resistance in an envelope filled with inert gas, such as hydrogen, to serve as the field resistance. The characteristic curve thereof is so steep that the resistance will increase at such a rapid rate as to avoid overswing in voltage. Its employment will further reduce sparking at the contacts due to the characteristic low resistance at the moment the contacts open. Not only is the rotary relay of the present invention adapted to accurate regulation of line voltages of both D. C. and A. C. generators but can be efliciently employed to provide cross-current compensation where several generators are operated in parallel on common buses. This may be accomplished by using a rotary regulator for each generator and by slight biasing oi the field windings of the different regulators. Further the provision of the control knob 20 provides effective and readily operable means for adjusting the voltage setting of the regulator.

It has been found that better overall results may be obtained, particularly when the rotary relay of the present invention is employed in regulating the voltage of an electrical generator, if a resilient mount for the relatively fixed contact be employed. This may be accomplished by fixing one end of a leaf spring to the inside face of the supporting cross-member 25 and mounting the relatively fixed contact 21 or l2! thereon. with the leaf spring spaced from the cross-member in the vicinity of the contact mount. Such a structure is shown by way of example in Fig. 9. A leaf spring 41 is fixed to the inside of crossmember 25, preferably at one end such as at 48. The free end 49 of the spring 41 is spaced from the cross-member 25 to permit movement of the former toward the latter and carries the relatively fixed contact 21. A similar leaf spring 50 is mounted on the outside of cross-member 25 in a similar manner with one end fixed thereto at ii. The free end 52 thereof may be extended to be engaged by an adjusting screw 53 mounted in the cross-member 25. A linking arm 84 preferably extends through an enlarged hole 55 in the cross-member 25 and is connected at its opposite ends to the leaf springs 41 and 50.

In operation of the rotary relay as a voltage regulator, equipped with the resilient mount of the relatively fixed contact as taught in Fig. 9, tendency completely to break the circuit, which includes contacts 21 and H, upon slight axial movement of the rotor will be reduced. Such a resilient mount will permit axial play of the relatively fixed contact without destroying the desirable feature of variable contact pressure and resistance. Less fiexure of the leaf springs results in less spring biasing of the relatively fixed contact 21, thus providing less contact pressure and more contact resistance, and vice versa. Adjustment of the screw 53 will vary the initial biasing force of'the springs 41 and 50.

The structure shown in Fig. 9 also assures proper alignment of the face of the relatively fixed contact 21 with the face of the axially moved contact 31 in the various axial positions thereof. Their parallelism is maintained thereby. It eliminates tendency of the face of contact 21 to be moved into a plane at an angle to the plane of the face of contact 3| as the leaf sprin support of contact 21 is flexed thereby avoiding possible reduction in the contact area and localized excessive wearing.

In the drawings particularly in Figs. 1, 2 and 6,

it is proposed to mount the rotary relay in a position where normally the rotor rotates in an axially displaced position above the stator and is biased upwardly to such position by the biasing force of the spring 2| so that when the field force of the field winding of the rotary relay becomes strong enough to overcome the biasing force of the spring 21', the rotor is pulled down into alignment with the stator. This is preferred as a measure of safety since, should the biasing spring 2| break, force of gravity will cause the rotor to fall into alignment with the stator thereby separating the contacts in the shunt circuit resulting in the insertion of all of the resistance of the field resistance in the field circuit of the generator to avoid danger of over voltage. It will be understood, however, that it is possible to operate the rotary relay in other positions such as with the axis of the rotor arranged horizontally or even with the device reversed where in the latter case the rotor is biased axially down to a position displaced from the stator by both the biasing force of the spring and the force of gravity.

It will thus be seen that the objects set forth above, among others, have been efliciently attained by the present invention and since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

l A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially dis placed position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other.

2. A rotary relay for controlling electricalcircuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, means iloatingly mounting said rotor for axial movement thereof, said rotor normally being biased to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other.

3. A rotary relay for controlling electrical circuits comprising, in combination, an electric mo tor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, means floatingly mounting said rotor for axial movement thereof, means resiliently biasing said rotor to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling fiow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other.

4. A rotary relay for controlling electrical circuits comprising in combination, an electric motor-having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, means floatingly mounting said rotor for axial movement thereof, said rotor normally being biased to an axially displaced position with respect to said stator, mean for adjustably varying the biasing force which axially displaces the rotor, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other.

5. A rotary relay for controlling electrical circuits comprising, in combination. an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, means floatingly mounting said rotor for axial movement thereof, said rotor normally being biased to an axially displaced position with respect to said stator, means for adjusting the displacement of said rotor, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one 01 said contacts with respect to the other.

6. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one oi. which includes a field winding adapted to be supplied with control current, means floatingly mounting said rotor for axial movement thereof, resilient means biasing said rotor to an axially displaced position with respect to said stator, means for varying the biasing force of said resilient means, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axialmovement to move one of said contacts with respect to the other.

7. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator, said stator com prising a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator. a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other.

8. A rotary relay for controlling electrical circuits comprising in combination, an electric motor having a rotor and a stator, said stator comprising a field winding adapted to be supplied with control current, means fioatingly mounting said rotor for axial movement thereof, said rotor normally being biased to an axially displaced position with respect to said stator, means for adjustably varying the biasing force which axially displaces the rotor, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling how of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other.

9. A rotary relay for controlling electrical cir cuits comprising, in combination, an electric motor having a rotor and a stator, said stator comprising a field winding adapted to be supplied with control current, means fioatlngly mounting said rotor for axial movement thereof, resilient means biasing said rotor to an axially displaced position with respect to said stator, means for varying the biasing force of said resilient means. a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling fiow of current therethrough, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other.

10. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being fioatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling fiow of current therethrough, one of said cditacts being connected to said rotor for rotary and axial movement therewith, and means supporting the other contact for cooperation with the first-mentioned contact.

11. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of cooperating contact adapted to be connected in circuit with an electrical device for controlling fiow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, and means supporting the other contact in a relatively fixed position with respect to the first-mentioned contact.

12. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, means i'loatingly mounting said rotor for axial movement thereof, means resiliently biasing said actor to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controllin flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, and means supporting the other contact in a relatively fixed position with respect to the first-mentioned contact.

13. A rotary relay for controlling electrical circuits comprising in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, means fioatingly mounting said rotor for axial movement thereof, said rotor normally being biased to an axially displaced position with respect to said stator, means for adjusts ably varying the biasing force which axially displaces the rotor, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, one of said contact being connected to said rotor for rotary and axial movement therewith, and means supporting the other contact in a relatively fixed position with respect to the first-mentioned contact.

14. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, means floatingly mounting said rotor for axial movement thereof, resilient means biasing said rotor to an axially displaced position with respect to said stator, means for varying the biasing force or said resilient means, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, and means supporting the other contact in a relatively fixed position with respect to the first-mentioned contact.

15. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator, said stator comprising a field winding adapted to be supplied with control current, a rotary shaft carrying said rotor, means rotatably and fioatingly supporting said shaft for rotation and axial movement thereof, said shaft normally being biased to an axially shifted position with said rotor displaced axially with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, means mounting one of said contacts on an end of said shaft for rotary and axial movement therewith, and other means supporting the remaining contact for cooperation with the first-mentioned contact.

16. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator, said stator comprising a field winding adapted to be supplied with control current, a rotary shaft carrying said rotor, means rotatably and floatingly supporting said shaft for rotation and axial movement thereof, resilient means biasing said shaft to an axially shifted position with said rotor displaced axially with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling fiow oi current therethrough, means mounting one of said contacts on an end of said shaft for rotary and axial movement therewith, and other means supporting the remaining contact for cooperation with the first-mentioned contact.

17. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator. said stator comprising a field winding adapted to be supplied with control current, a rotary shaft carrying said rotor, means rotatably and fioatingly supporting said shaft for rotation and axial movement thereof. resilient means biasing said shaft to an axially shifted position with said rotor displaced axially with respect to said stator. means for varying the biasing force of said resilient means, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough. means mounting one of said contacts on an end of said shaft for rotary and axial movement therewith, and other means supporting the remaining contact for cooperation with the first-mentioned contact.

18. A rotary relay for controlling electrical circuits comprising, in combination. an electric motor having a rotor and a stator. said stator comprising a field winding adapted to be supplied with control current. an electrically-conductive rotary shaft carrying said rotor, means rotatably and fioatingly supporting said shaft for rotation and axial movement thereof, a contact mounted on an end of said shaft for rotary and axial movement therewith, a cooperating contact, means supporting the latter in a relatively fixed position with respect to said rotary contact, resilient means abutting the other end of said shaft biasing the latter toward said relatively fixed contact to hold said contacts together under pressure with said rotor displaced axially with respect to said stator, current transfer means in contact with said shaft, and a pairof circuit terminals with one connected to said current transfer means and the other connected to said relatively fixed contact. said terminals being adapted to be connected in circuit with an electrical device for controlling flow of current therethrough.

19. A rotary relay for controlling electrical circuits comprising. in combination, an electric motor having a rotor and a stator. said stator comprising a field winding adapted to be supplied with control current, an electrically-conductive rotary shaft carrying said rotor, means rotatably and .noatingly supporting said shaft for rotation and axial movement thereof, a contact mounted on an end of said shaft for rotary and axial movement therewith, a cooperating contact, means supporting the latter in a relatively fixed position with respect to said rotary contact, resilient means abutting the other end of said shaft biasing the latter toward said relatively fixed contact to hold said contacts together under pressure with said rotor displaced axially with respect to said stator; said resilient means comprising electrically-conducting bearing means abutting the end of said shaft for current transfer, axially adjustable abutment means and a spring positioned between said abutment means and said bearing means biasing the latter; a circuit terminal electrically connected to said bearing means and another circuit terminal electrically connected to said relatively fixed contact.

20. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with current from a controlling circuit, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of contacts adapted to be connected in the controlling circuit of an electrical device, and means mechanically connected to said rotor to cause the latter in its axial movement to move one of said contacts with respect to the other for varying the contact pressure thereof to vary fiow of current through the controlling circuit and to make and break that circuit.

21. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being fioatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough. one of said contacts being connected to said rotor for rotary and axial movement therewith. and means supporting the other contact in a relatively fixed position with respect to said rotary contact, one of said contacts having a relatively smooth contact face and the other of said contacts having cutting edges on its contact face to condition the relatively smooth contact face during contact rotation.

22. A rotary relay for controlling electrical circuits comprising. in combination, an electric motor havin a rotor and a stator one of which includes a field winding adapted to be supplied with control current. said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator. a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, and means supporting the other contact in a relatively fixed position with respect to said rotary contact. said relatively fixed contact having a relatively smooth contact face and said rotary contact having a relatively smooth contact face interrupted by a transverse groove providing cutting edges to condlflon the forme during rotation o the letter.

23. A rotary relay for controlling electrical circuits comprising, in combination. an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controllin flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement-therewith, and means supporting the other contact in a relatively fixed position with respect to said rotary contact, said relatively fixed contact having a relatively smooth contact face and said rotary contact having a relatively smooth contact face interrupted by a transverse groove having side walls extending substantially in the direction of the axis of totation of said contact and meeting with the contact face at sharp angles thereby providing cutting edges to condition the former during rotation of the latter.

24. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which in cludes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially dis- 15 placed position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, and means sup por ing the other contact in a relatively fixed position with respect to said rotary contact, said 1 elatively fixed contact having a relatively smooth contact face and said rotary contact having a.

cludes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controllin flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, and means supporting the other contact in a relatively fixed position with respect to said rotary contact, said relatively fixed contact having a relatively smooth contact face and said rotary contact having a relatively smooth contact face interrupted by transverse intersecting grooves each having side walls of substantial depth extending substantially in the direction of the axis of rotation of said contact and meeting with the contact face at sharp angles thereby providing cutting edges to condition the former and to set up a sparkquenching fan action during rotation of the latter.

26. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a, rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of co-cperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, one 01 said contacts being connected to said rotor for rotary and axial movement therewith, and means resiliently supporting the other contact for cooperation with said rotary contact.

27. A rotary relay for controlling electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, a pair of spaced apart laterally extending arms each having a free end, means connecting the other ends together in spaced apart relation and supporting the same, and means fioatingly supported by said arms and connecting the free ends thereof together in spaced apart relation, said floatingly supported means supporting the other contact for cooperation with said rotary contact.

28. A rotary relay for controllin electrical circuits comprising, in combination, an electric motor having a rotor and a stator one of which includes a field winding adapted to be supplied with control current, said rotor being floatingly mounted and normally biased to an axially displaced position with respect to said stator, a pair of cooperating contacts adapted to be connected in circuit with an electrical device for controlling flow of current therethrough, one of said contacts being connected to said rotor for rotary and axial movement therewith, a pair of spaced apart laterally extending leaf springs each having a free end, mounting means fixedly supporting the other ends of said leaf springs in spaced apart relation, and a member floatingly supported by said leaf springs with each of the latter being fixed thereto in spaced apart relation, said member having a portion extending beyond one of said springs terminating with the other contact for cooperation with said rotary contact.

CECIL PATRICK MOLYNEUX. VERNON D. ROOSA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,766,049 Trogner June 24, 1930 1,403,701 McCullough Jan. 17, 1922 2,274,938 Ray Mar. 3, 1942 2,069,610 Juillard Feb. 2, 1937 1,062,380 Apple May 20, 1913 1,146,954 Ricketts July 20, 1915 1,466,654 Clough Aug. 28, 1923 

